if added {
		// Write the string to the buffer.
		systemstack(func() {
			t.writeString(gen, id, s)
		})
	}
	return id
}

// emit emits a string and creates an ID for it, but doesn't add it to the table. Returns the ID.
func (t *traceStringTable) emit(gen uintptr, s string) uint64 {
	// Grab an ID and write the string to the buffer.
	id := t.tab.stealID()
	systemstack(func() {
		t.writeString(gen, id, s)
	})
	return id

func newNowritebarrierrecChecker() *nowritebarrierrecChecker {
	c := &nowritebarrierrecChecker{
		extraCalls: make(map[*ir.Func][]nowritebarrierrecCall),
	}

	// Find all systemstack calls and record their targets. In
	// general, flow analysis can't see into systemstack, but it's
	// important to handle it for this check, so we model it
	// directly. This has to happen before transforming closures in walk since

		// g0 stack without switching g. We can't safely make
		// a call in this state. (We can't even safely
		// systemstack.)
		return debugCallSystemStack
	}

	// Switch to the system stack to avoid overflowing the user
	// stack.
	var ret string
	systemstack(func() {
		f := findfunc(pc)
		if !f.valid() {
			ret = debugCallUnknownFunc
			return
		}

		name := funcname(f)

//go:nosplit
func (th *vdsoTimehands) getHPETTimecounter() (uint32, bool) {
	idx := int(th.x86_hpet_idx)
	if idx >= len(hpetDevMap) {
		return 0, false
	}

	p := atomic.Loaduintptr(&hpetDevMap[idx])
	if p == 0 {
		systemstack(func() { initHPETTimecounter(idx) })
		p = atomic.Loaduintptr(&hpetDevMap[idx])
	}
	if p == ^uintptr(0) {
		return 0, false
	}
	return *(*uint32)(unsafe.Pointer(p + _HPET_MAIN_COUNTER)), true
}

	if refill {
		w = w.refill(traceNoExperiment)
	}
	return w, refill
}

// flush puts w.traceBuf on the queue of full buffers.
func (w traceWriter) flush() traceWriter {
	systemstack(func() {
		lock(&trace.lock)
		if w.traceBuf != nil {
			traceBufFlush(w.traceBuf, w.gen)
		}
		unlock(&trace.lock)
	})
	w.traceBuf = nil
	return w
}

	// while sleeping.
	acquireLockRankAndM(rw.readRank)
	lockWithRankMayAcquire(&rw.rLock, getLockRank(&rw.rLock))

	if rw.readerCount.Add(1) < 0 {
		// A writer is pending. Park on the reader queue.
		systemstack(func() {
			lock(&rw.rLock)
			if rw.readerPass > 0 {
				// Writer finished.
				rw.readerPass -= 1
				unlock(&rw.rLock)
			} else {
				// Queue this reader to be woken by
				// the writer.

		tp       unsafe.Pointer
	}{_CLOCK_MONOTONIC, unsafe.Pointer(&ts)}
	if errno := libcCall(unsafe.Pointer(abi.FuncPCABI0(clock_gettime_trampoline)), unsafe.Pointer(&args)); errno < 0 {
		// Avoid growing the nosplit stack.
		systemstack(func() {
			println("runtime: errno", -errno)
			throw("clock_gettime failed")
		})
	}
	return ts.tv_sec*1e9 + int64(ts.tv_nsec)
}
func clock_gettime_trampoline()

//go:nosplit

	// Do this check last because it is more expensive and rarely true.
	// If it is false the expense doesn't matter since we are crashing.
	if inPersistentAlloc(uintptr(unsafe.Pointer(dst))) {
		return
	}

	systemstack(func() {
		println("write of unpinned Go pointer", hex(uintptr(src)), "to non-Go memory", hex(uintptr(unsafe.Pointer(dst))))
		throw(cgoWriteBarrierFail)
	})
}

	w, _ = w.ensure(1 + traceBytesPerNumber /* traceEvFrequency + frequency */)

	// Write out the string.
	w.byte(byte(traceEvFrequency))
	w.varint(traceClockUnitsPerSecond())

	// Immediately flush the buffer.
	systemstack(func() {
		lock(&trace.lock)
		traceBufFlush(w.traceBuf, gen)
		unlock(&trace.lock)
	})

//go:nosplit
func semawakeup(mp *m) {
	atomic.Xadd(&mp.waitsemacount, 1)
	ret := thrwakeup(uintptr(unsafe.Pointer(&mp.waitsemacount)), 1)
	if ret != 0 && ret != _ESRCH {
		// semawakeup can be called on signal stack.
		systemstack(func() {
			print("thrwakeup addr=", &mp.waitsemacount, " sem=", mp.waitsemacount, " ret=", ret, "\n")
		})
	}
}

func osinit() {
	ncpu = getncpu()
	physPageSize = getPageSize()
}